Blind Intubation Techniques
Steven A. Godwin
DESCRIPTION
Blind intubation techniques are those methods of airway management that are done without visualization of the larynx or glottis. Both blind nasotracheal intubation (NTI) and digital tracheal intubation (DTI) use indirect indicators of airway identification in lieu of direct vision laryngoscopy. NTI relies on listening to and feeling air movement, whereas DTI depends on the provider’s ability to use tactile senses to distinguish airway anatomy as the tube is inserted. Other methods of airway management that do not require direct visualization of the glottis, but that do require specialized equipment, such as lighted stylets and gum elastic bougies, are discussed in other chapters. Some consider flexible bronchoscopic intubation as being a “blind” technique as the actual passage of the endotracheal tube (ETT) through the vocal cords into the trachea is not visualized.
BLIND NASAL INTUBATION
Although NTI was widely used in emergency departments (EDs) in the past, it has been supplanted by superior techniques of oral intubation with neuromuscular blockade, even in the prehospital setting. In general, NTI has a number of serious drawbacks, and few advantages when compared with the other techniques that are now commonly used for emergency airway management. NTI has largely fallen out of favor in the ED because it takes longer, has a higher failure rate, has a higher complication rate, and requires smaller tube sizes than oral rapid sequence intubation (RSI). However, despite these inherent problems, NTI is still considered an important skill because it may be useful in certain difficult airway situations, particularly in departments without flexible endoscopic intubation capability.
Indications and Contraindications
As clinicians become more facile and comfortable with neuromuscular blockade and a variety of other approaches, the one remaining indication for NTI may be the spontaneously breathing patient with an identified difficult airway, for whom RSI is judged to be inadvisable (see Chapters 2 and 3). NTI is achieved by listening to the patient’s spontaneous respirations through the tube and, therefore, should not be attempted in the apneic patient. It is relatively contraindicated in combative patients; in those with anatomically disrupted or distorted airways (e.g., neck hematoma, upper airway tumor, etc.); in cases of increased intracranial pressure; in the context of severe facial trauma with suspected basal skull fracture; in upper airway infection, obstruction, or abscess (e.g., Ludwig angina, epiglottitis, etc.); and in the presence of coagulopathy. NTI should be performed with great reservation on any patient who needs rapid intubation because, despite optimistic claims to the contrary, intubation usually requires several minutes to perform using this technique, and significant oxygen desaturation can occur. Therefore, it is a poor choice for patients with respiratory failure, such as the asthmatic patient in extremis, who cannot be oxygenated during a protracted nasal intubation attempt. In addition, one of the primary indications for NTI in the past, the patient with multiple injuries and potential cervical spine injury, has been discarded, and oral RSI with inline stabilization is now the recommended route (see Chapter 31).
Technique
1. If the patient is awake, explain the procedure. This is a crucial step that is often neglected. If the patient becomes combative during intubation, the attempt must cease because epistaxis, turbinate damage, or even pharyngeal perforation may ensue. A brief, reassuring explanation of the procedure, its necessity, and anticipated discomfort may avert this undesirable situation. Preoxygenate the patient with 100% oxygen as for RSI
(see Chapter 19), if possible. Try to avoid bagging with positive pressure if spontaneous ventilation is adequate.
(see Chapter 19), if possible. Try to avoid bagging with positive pressure if spontaneous ventilation is adequate.
2. Choose the nostril to be used. Inspect the interior of the naris, with particular reference to the septum and turbinates. It may help to occlude each nostril in turn and listen to the flow of air through the orifices. If there appears to be no clear favorite, the right naris should be selected because it better facilitates passage of the tube with the leading edge of the bevel laterally placed.
3. Instill two or three drops of Neo-Synephrine (phenylephrine) or oxymetazoline nasal solution into each nostril. This will vasoconstrict the nasal mucosa and may make tube passage easier. The incidence of epistaxis may also be reduced, although there is little evidence to that effect. It may also be helpful to soak two or three cotton-tipped applicators in the vasoconstrictor solution and place them gently and fully into the naris until the tip touches the nasopharynx. This provides vasoconstriction at the area that is often most difficult to negotiate blindly with the ETT. Nasal topical anesthesia may then be placed as time permits. Insertion of a 4% cocaine pack or instillation of 2% lidocaine jelly will provide anesthesia for the nose. The oral cavity can be sprayed with 4% lidocaine or a similar spray, and, if desired, the pharynx may be anesthetized similarly. An alternative is to nebulize a solution of 4 ml of 4% lidocaine with 1 ml of 0.5% Neo-Synephrine in a gas-powered nebulizer, as one would do with albuterol. This takes approximately 5 to 10 minutes but provides reasonable anesthesia and is well tolerated. Still another suggested method involves insertion of an absorbent nasal tampon (as is used for epistaxis) and application of several milliliters of 2% lidocaine with 1:100,000 epinephrine. Cricothyroid puncture with instillation of 5 to 10 ml of 1% to 2% lidocaine is often advocated. This technique is reasonably simple and effective but usually produces coughing, perhaps an undesirable result. Importantly, complete anesthesia of the glottis may not be desirable in all cases. Advancing the tube during the inspiratory phase of a cough sometimes allows immediate intubation of an otherwise elusive trachea.
4. Lubricate the tube and the nostril. The use of 2% lidocaine jelly has been advocated, but it will not normally be in contact with the nasal mucosa long enough to result in anesthesia. However, the jelly is an adequate lubricant and is not harmful, so it is a reasonable choice.
5. Select the appropriate size of ETT. In general, the tube should be the largest one that will fit through the nostril without inducing significant trauma. In most patients, a tube with an internal diameter (ID) of 6.0 to 7.5 cm will suffice. A smaller tube will fit through a difficult or tight space better than a larger tube. Test the ETT cuff for leaks.
6. Because the patient is often seated, it is probably easiest for a right-handed person to intubate from the patient’s left side. This allows the right hand to be used for the intubation, while the left hand manipulates the location of the larynx and provides feedback to the right hand. By leaning slightly forward between the two hands, the operator can listen to the breath sounds and guide the tube into place. If the patient is supine, the operator will position him- or herself immediately above the patient’s head. Positioning the head as for oral intubation is worthwhile, if possible. The so-called sniffing position, with the neck flexed on the body and the head extended on the neck, optimizes the alignment of the mouth and pharynx with the vocal cords and trachea (see Chapter 12). Care must be taken to avoid overextension, however, which causes the tube to pass anteriorly to the epiglottis. A small towel may be placed behind the patient’s occiput to help maintain this relationship.
7. Some advise gently inserting a gloved and lubricated little finger into the chosen nostril as deeply as possible to check for patency and to dilate the nostril to accept the tube as atraumatically as possible. The intubation sequence begins by gently inserting the ETT into the nostril with the leading edge carefully avoiding the rich vascular area of the anterior septum. For consistency, the remainder of this discussion assumes a right naris intubation by a right-handed operator. The tube should be turned so that the leading edge of the bevel is “out” (i.e., away from the septum). This will minimize the chances of septum injury and epistaxis. This also orients the natural curve of the ETT tube with the natural curve of the airway.
The major nasal airway is located below the inferior turbinate and the placement of the ETT should follow the floor of the nose backward. The tip of the tube should be directed caudad at an approximately 10° angle to follow the gently downsloping floor of the nose (see Chapter 4). This entire process should be done slowly and with meticulous care. Once the nasal portion of the airway is navigated, inciting epistaxis is unlikely. When the tip of the tube approaches the posterior pharynx, resistance will often be felt, particularly if the leading edge of the ETT enters the depression in the nasopharynx where the eustachian tube enters. At this point, it is possible to penetrate the nasopharyngeal mucosa with the ETT and dissect submucosally if care is not taken (see Chapter 4
The major nasal airway is located below the inferior turbinate and the placement of the ETT should follow the floor of the nose backward. The tip of the tube should be directed caudad at an approximately 10° angle to follow the gently downsloping floor of the nose (see Chapter 4). This entire process should be done slowly and with meticulous care. Once the nasal portion of the airway is navigated, inciting epistaxis is unlikely. When the tip of the tube approaches the posterior pharynx, resistance will often be felt, particularly if the leading edge of the ETT enters the depression in the nasopharynx where the eustachian tube enters. At this point, it is possible to penetrate the nasopharyngeal mucosa with the ETT and dissect submucosally if care is not taken (see Chapter 4
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